Add OPTIONS_DEFINE=DOCS for ports with %%PORTDOCS%% in the plist.
Where possible, correct a few instances where PORTDOCS was being used
to flag stuff in EXAMPLESDIR. For some ports, mostly those owned by
ruby@, PORTDOCS is applied to pretty much everything whether it's
documentation or example.

Update to libmpc version 1.0.1 which brings the following fixes:
- Switched to automake 1.11.6, see CVE-2012-3386.
- #14669: Fixed extraction of CC from gmp.h.
- Fixed case of intermediate zero real or imaginary part in mpc_fma,
found by hydra with GMP_CHECK_RANDOMIZE=1346362345.
This is on top of the following changes from version 1.0
- Licence change towards LGPLv3+ for the code and GFDLv1.3+ (with no
invariant sections) for the documentation.
- 100% of all lines are covered by tests
- Renamed functions
. mpc_mul_2exp to mpc_mul_2ui
. mpc_div_2exp to mpc_div_2ui

Replace USE_GCC=4.6+ and USE_GCC=4.4+ by USE_GCC=yes.
Right now this is a noop in the former case and a noop in the latter
case unless lang/gcc44 has been installed explicitly.
This puts a bit more emphasis on standardizing on a canonical version
"current" GCC and makes it easier to update that canonical version
by changing the default in Mk/bsd.gcc.mk and updating the lang/gcc port.
That is, USE_GCC=yes means "use a decent/modern version of GCC" without
having to worry about details.
Approved by: portmgr (bdrewery)